This invention relates to inkjet printers having an auxiliary coating apparatus for applying a supplemental fluid to print media, and apparatus and methods of supplying the fluid.
Inkjet printers typically use a printhead mounted on a carriage that is moved relative to a print media, such as paper. As the printhead is moved relative to the print media, a control system activates the printhead to deposit or eject ink droplets onto the print media to form images and text. Ink is provided to the printhead by a supply of ink that is either integral with the printhead, as in the case of a disposable print cartridge, or by a supply of ink that is replaceable separate from the printhead. With separately replaceable ink supplies, the ink supply is replaced when exhausted, and the printhead is then replaced at the end of the printhead useful life.
Inkjet printers have typically had several shortcomings. First, image quality is dependent upon the print media. Optical density of a printed image can vary greatly with the print media or substrate being printed upon. Images may have poor edge acuity, color-to-color bleed, and low chroma, as well as low waterfastness and a tendency to smudge. Second, ink drying time can be a significant factor in limiting printer throughput.
Techniques to address these shortcomings often involve the application of a supplemental fluid to the print media, either before printing or after printing. In underprinting, a transparent fluid is applied to the substrate prior to ink deposition, which helps to stratify the colorant to the surface of the paper, reduces wicking, and improves color performance.
Two-part inkjet printing is composed of a printing ink and a substance commonly referred to as a xe2x80x9cfixerxe2x80x9d. Typically, fixer is applied to the media via an additional printhead or other applicator mechanism prior to printing the ink. The ink reacts with the fixer upon contact on the media surface, immobilizing the ink colorant close to the media surface. This technique provides a more consistent dot shape across media types, faster dry times, and better durability, among other advantages.
The principle disadvantage of using a fixer or other supplemental fluid, from the perspective of the printer operator, is the need to provision the printer system with an additional consumable. In a typical prior art multi-part printing system, the printer operator must monitor and replace not only the ink supplies, but also a separate fixer supply.
Accordingly, there is a need for apparatus and methods which enable multi-part printing, without the disadvantages imposed by an additional printer consumable.
Embodiments of the present invention comprise a reservoir system for supplemental fluids in a system (such as an inkjet printer), in which supplies of a supplemental fluid are included in two or more replaceable primary fluid containers (such as ink containers). A controller may then selectively connect a supply of the supplemental fluid to the device utilizing the supplemental fluid (such as a fixer applicator).
Among other advantages, the present invention allows the use of fixer in an inkjet printer, giving all of the print quality, durability, and throughput (drytime) advantages of a two-part system, without the printer user ever knowing that the printing system requires this additional consumable. By maintaining the number of consumables in the inkjet printing system to the total number of inks, the printer user is not required to locate, purchase, and replace additional consumables during the lifetime of the printer. The present invention thus provides the benefits of using a fixer or other supplemental fluid in an inkjet printing system without increasing the user intervention rate.
Other aspects and advantages of the present invention will become apparent from the following detailed description, taken in conjunction with the accompanying drawings, illustrating by way of example the principles of the invention.